March 2017

Need Roof Board Options And Technical Expertise?
We’ve Got You Covered.

Pat Grotlisch and Scott Hughes

Coverboard plays an integral role in a roof system’s lifetime performance. The benefits of specifying coverboard include extending the roof life; protecting insulation from weather (hail/storms) and foot traffic (not to mention equipment); improving fire resistance, thermal performance and the system’s wind uplift rating; and decreasing the amount of noise that enters a building. It also provides a smooth, flat surface for the membrane. In addition, it will help your client save energy over the long haul.

Now that we’ve explored the benefits of using a coverboard, the question is which one. When specifying a coverboard, aspects to consider include: will it be a component of a mechanically attached system or an adhered roofing system? Will the building have a high humidity environment? At National Gypsum, we have three excellent options of DEXcell® BRAND Roof Boards and they will all extend the life of your client’s investment. Contingent upon your building design, one (or more) will match your requirements. When choosing a coverboard, consider the characteristics of the specific roof assembly, and take into account the board’s compatibility with the assembly.

Let us know if you would like more information about DEXcell®. If you have not already specified these roof boards, we would like to introduce you to them. As always, we are here to help you design and build better.

The Latest On DEXcell® brand Roof Boards

To date, DEXcell® BRAND has more than 45,000 Factory Mutual (FM) assemblies approved as either a coverboard or thermal barrier. DEXcell® has test approvals with Underwriters Laboratory (UL) for thermal barrier and spread of flame; State of Florida; FM (some complete, some ongoing); and Miami Dade Approval (we continue ongoing tests for high-wind assemblies). Membrane manufacturer partners (DEXcell is listed as a component in their systems) include: Johns Manville; Polyglass; Soprema U.S., FiberTite, Duro-Last, Kemper, Acrylabs, and Derbigum. DEXcell® products are currently manufactured in six U.S. facilities.

"Few parts of a building are more important than the roof. If the roof leaks, your client’s investment in people and equipment are at risk. Specifying DEXcell® brand coverboards protects that investment by creating a more durable roof. DEXcell® helps to protect the roof from the foot traffic of maintenance people, hail and wind damage. For your clients that want to keep their buildings for a long time, specifying DEXcell can help lengthen the performance of your carefully chosen roofing membrane."
- Scott W. Hughes

"Last year, I worked with a San Francisco-based architect who designed a fire station with a Blue Roof and specified a cement board coverboard. The fire station was designed with a Blue Roof as part of the storm management system. The Blue Roof was designed to hold a maximum of 5½” of water and slowly release it back into the storm drain system over a 24-48-hour time period. The manufacturer of the waterproofing system recommended using PermaBase® brand Cement Board as the coverboard. In addition to DEXcell® brand Cement Board, National Gypsum Company also offers DEXcell® brand Glass Mat Roof Boards for mechanically attached systems and DEXcell® brand FA Glass Mat Roof Boards for fully adhered systems.”
- Pat Grotlisch

Product Overview

Three Outstanding Products

  • Specify DEXcell® BRAND Cement Roof Board as a coverboard in roofing assemblies that will be exposed to moisture or high humidity. DEXcell® Cement Board is manufactured of Portland cement, lightweight aggregate and glass mesh that provides an exceptionally hard, durable surface.

All three DEXcell® brand Roof Boards:

  • Protect and support the roof membrane;
  • Provide increased fire and moisture resistance;
  • Offer acoustical enhancement;
  • Reduce the potential for penetration damage to the membrane.

They also all serve as substrates for vapor retarders and/or continuous substrates for the application of roofing membranes. Use any of them as a substrate board and for thermal protection in roofing assemblies.

Project Profile

State-Of-The-Art KMG Chemical Manufacturing Facility


KMG-Pueblo, Colorado
Jewett Roofing

This facility manufactures high purity acids, solvents and other wet chemicals used to etch and clean silicon wafers in the production of semiconductors. An on-site 100,000-square-foot, temperature-controlled warehouse maintains material storage integrity. To provide excellent coverage for this important inventory, Jewett Roofing constructed the roof using 260,000 square feet of DEXcell® brand FA Glass Mat Roof Board.

Continuing Education

Now is a good time to begin fulfilling your CEUs. Consider taking one of these:

Advantages of Using Coverboards In Low-Slope Roofing Assemblies
1 hour/AIA 1 HSW/LU
High Performance Gypsum: Protect Against Mold, Moisture And Exposure
1 hour/AIA 1 HSW/LU

Take Advantage of Our Complimentary Specification Reviews

Would you like an architect to review your specifications, at no cost? National Gypsum’s in-house architects and certified Construction Document Technology (CDT) specialists are now available for Complimentary Architectural Specification Reviews. This free service provides peace of mind and helps your project stay on track. Contact your Construction Design Manager today to request a review, and let us help you.


Amy Hockett
National Marketing Manager, Architectural Services & Sustainability

Pat Grotlisch

Frank Fuller

Alan Zeedyk
Gulf / Southeast

Thad Goodman
Central / Midwest

Scott Hughes
Northeast / Atlantic

Trang Schwartz
Architectural Specialist